http://ngmdb.usgs.gov/Prodesc/ 2008-12-12 weekly 0.8 http://ngmdb.usgs.gov/ngmdb/ 2008-12-12 monthly http://ngmdb.usgs.gov/Geolex/ 2008-12-12 monthly http://ngmdb.usgs.gov/Geolex/NewUnits/ 2008-12-12 monthly http://ngmdb.usgs.gov/Info/ 2008-12-12 monthly http://ngmdb.usgs.gov/MapProgress/ 2008-12-12 monthly http://ngmdb.usgs.gov/Other_Resources/rdb_es.html 2008-12-12 monthly http://ngmdb.usgs.gov/Other_Resources/rdb_topo.html 2008-12-12 monthly